The ability to place an emergency services call by dialing 9-1-1 has become widespread throughout the United States. When a 9-1-1 call is placed, it is typically answered at a public safety answering point (PSAP). However, there are many PSAPs throughout the United States, each serving a particular area, such as a city, county, or metropolitan area. The public switched telephone network (PSTN) can route a 9-1-1 call to the appropriate PSAP, i.e., the PSAP that serves the caller's area, because the caller's telephone number is associated with a fixed location.
Increasingly, however, packet networks are being used for voice or video communications, including emergency services calls. Such voice-over-packet or video-over-packet (both VoP) networks often route calls that are placed by client devices that can change their point of connectivity to the VoP network. For example, a mobile station may be able to place calls over the VoP network from different access points at different locations. In many cases, the access points are wireless access points that wirelessly communicate with mobile stations using an IEEE 802.11x or other wireless local area network (WLAN) protocol. Because of this mobility, mobile stations and their associated telephone numbers may not be reliably associated with fixed geographic locations. Even so, it is desirable for a mobile station user to be able to dial 9-1-1 from any location and have the call routed through the VoP network to the appropriate PSAP, i.e., the PSAP that serves the user's current location.
Accordingly, it would be desirable to provide methods and systems that facilitate VoP emergency service calls to appropriate PSAPs.